The non-protein amino acid β-alanine is a precursor of pantothenate (vitamin B5) in all plants; and the osmoprotectant β-alanine betaine in most members of Plumbaginaceae (Hanson et. al., 1991). β-Alanine betaine is a product of three sequential methylations of β-alanine (Rathinasabapathi et. al., 2001). While beta-alanine itself can be an osmoprotectant, in certain plants it is methylated to a more effective osmoprotectant called beta-alanine betaine.
Bacteria make beta-alanine by decarboxylating aspartic acid. In Escherichia coli, this reaction is catalyzed by the product of panD gene encoding L-aspartate-α-decarboxylase. Aspartate decarboxylation reaction is not known in plants. Plants appear to use a variety of other ways to synthesize beta-alanine. Thus, engineering strategies to increase β-alanine pool in plants has potential applications for improving nutritional quality, yield and abiotic stress tolerance of crops.